Communication between a plurality of medical devices using time delays between communication pulses to distinguish between symbols

Abstract

Systems and methods for communicating between medical devices. In one example, an implantable medical device comprising may comprise one or more electrodes and a controller coupled to the electrodes. The controller may be configured to receive a first communication pulse at a first communication pulse time and a second communication pulse at a second communication pulse time via the one or more electrodes. The controller may further be configured to identify one of three or more symbols based at least in part on the time difference between the first communication pulse time and the second communication pulse time.

What is claimed: 
     
       1. A method for communicating between a plurality of medical devices, the method comprising:
 generating, with a first medical device, a first non-pacing communication pulse at a first time and a second non-pacing communication pulse at a second time; 
 receiving, with a second medical device, the first non-pacing communication pulse at a third time and the second non-pacing communication pulse at a fourth time; 
 determining, by the second medical device, one of three or more symbols based at least in part on the time difference between the third time and the fourth time, wherein:
 a “0” symbol is determined if the difference between the third time and the fourth time is in a range of 350 to 450 microseconds; 
 a “1” symbol is determined if the difference between the third time and the fourth time is in a range of 550 to 700 microseconds; and 
 a synchronization symbol is determined if the difference between the third time and the fourth time is in a range of 800 to 1100 microseconds. 
 
 
     
     
       2. The method of  claim 1 , further comprising determining, by the second device, an end of frame symbol if, after receiving a non-pacing communication pulse, a threshold amount of time expires without receiving another non-pacing communication pulse. 
     
     
       3. The method of  claim 1 , wherein the first non-pacing communication pulse and the second non-pacing communication pulse are sub-threshold conducted communication pulses that do not capture a heart of a patient, and wherein:
 the first medical device delivers the first non-pacing communication pulse and the second non-pacing communication pulse to tissue of the patient; and 
 the second medical device receives the first non-pacing communication pulse and the second non-pacing communication pulse from the tissue of the patient, wherein the second medical device is physically spaced from the first medical device. 
 
     
     
       4. The method of  claim 3 , wherein the first non-pacing communication pulse and the second non-pacing communication pulse each have a combination of an amplitude and a pulse width that do not capture the heart of the patient. 
     
     
       5. The method of  claim 3 , wherein the first non-pacing communication pulse and the second non-pacing communication pulse are galvanically conducted communication pulses. 
     
     
       6. The method of  claim 3 , wherein the first non-pacing communication pulse and the second non-pacing communication pulse comprise:
 sub-threshold conducted voltage pulses; 
 sub-threshold conducted current pulses; or 
 a combination of sub-threshold conducted voltage pulses and sub-threshold conducted current pulses. 
 
     
     
       7. The method of  claim 1 , wherein the first non-pacing communication pulse and the second non-pacing communication pulse comprise:
 monophasic pulses; 
 biphasic pulses; or 
 a combination of monophasic pulses and biphasic pulses. 
 
     
     
       8. The method of  claim 1 , wherein the first non-pacing communication pulse and the second non-pacing communication pulse comprise:
 rectangular pulses; 
 sinusoidal pulse; 
 sinc pulses; 
 gaussian pulses, 
 trapezoidal pulses; 
 triangular pulses; 
 a raised cosine pulses; or 
 a combination of any of the above pulses. 
 
     
     
       9. The method of  claim 1 , wherein the difference between the third time and the fourth time is measured based on a same corresponding feature in each of the first non-pacing communication pulse and the second non-pacing communication pulse. 
     
     
       10. The method of  claim 1 , wherein the first non-pacing communication pulse and the second non-pacing communication pulse are:
 radiofrequency signals; 
 optical signals; 
 acoustic signals; 
 magnetic signals; or 
 conducted signal. 
 
     
     
       11. A method for communicating data from a first medical device to a second medical device, the method comprising:
 communicating consecutive conducted communication pulses from the first medical device to the second medical device; and 
 receiving the consecutive conducted communication pulses at the second medical device, determining an amount of time between at least selected consecutive conducted communication pulses, determining one of three or more symbols for each determined amount of time based at least in part on the determined amount of time, wherein the three or more symbols comprise:
 a “0” symbol; 
 a “1” symbol; and 
 a synchronization symbol; and 
 
 storing the determined symbol in a memory. 
 
     
     
       12. The method of  claim 11 , wherein the first medical device communicates the conducted communication pulses at times other than during delivery of a pacing pulse and/or during a recharge portion of a pacing pulse. 
     
     
       13. The method of  claim 11 , wherein the first medical device comprises a leadless cardiac pacemaker (LCP), and the second medical device comprises a subcutaneous cardioverter. 
     
     
       14. An implantable medical device comprising:
 one or more electrodes; 
 a controller coupled to the one or more electrodes, the controller configured to receive a first communication pulse at a first communication pulse time and a second communication pulse at a second communication pulse time via the one or more electrodes; and 
 the controller further configured to identify one of three or more symbols based at least in part on the time difference between the first communication pulse time and the second communication pulse time, wherein the controller identifies:
 a “0” symbol if the difference between the first communication pulse time and the second communication pulse time corresponds to a first time difference; 
 a “1” symbol, if the difference between the first communication pulse time and the second communication pulse time corresponds to a second time difference; and 
 a synchronization system if the difference between the first communication pulse time and the second communication pulse time corresponds to a third time difference. 
 
 
     
     
       15. The implantable medical device of  claim 14 , wherein the first time difference corresponds to a first range of time, the second time difference corresponds to a second range of time and the third time difference corresponds to a third range of time, wherein the first range of time, the second range of time and the third range of time do not overlap one another.